Field of the Application
The application relates to a graphite thermal conductor, and particularly to a graphite thermal conductor and a method for manufacturing a graphite thermal conductor, and an electronic device which uses a graphite thermal conductor as a thermal conductive medium.
Description of Related Art
Due to their diverse functions and thin design appearance, thin mobile devices such as the smart phone and the tablet computer are very popular. These kinds of thin mobile devices are generally provided with components which generate heat such as central processing unit (CPU) or the like, thus a heat dissipation means is necessary to reduce the temperature of these heat generating components, in order to ensure the normal operation of the thin mobile devices. CPUs with higher efficiency are employed in the thin mobile devices, and the CPUs also generate more and more heat, thus employing a heat dissipation means which has a superior efficiency is necessary.
To avoid affecting the normal voice call function, fans which may produce noises cannot be employed for actively dissipating heat in the thin mobile devices (especially, smart phones). Therefore, in some kinds of thin mobile devices, micro heat pipes (i.e., heat pipe with a very thin thickness) are used for heat dissipation. The micro heat pipe may transmit the generated heat generated by the central processing unit of the thin mobile device to other components having comparatively lower temperature, for example, battery or housing of the thin mobile device. Due to limit of apparent thickness of the thin mobile device, in order to avoid the increase of thickness of the thin mobile device, the micro heat pipes are also designed thinner and thinner. On the contrary, the micro heat pipes of the thin mobile devices can withstand less and less energy wattage, and since the micro heat pipes are required to be bent due to space restriction in X-Y directions of the thin mobile device, the bending of the micro heat pipes may substantially reduce the efficiency and success rate of the inner circulation of the micro heat pipes. However, in the case of the thickness being extremely small, the fluid (including liquid and gas) within the micro heat pipe becomes hard to flow, and thereby causing poor stability of heat dissipation of the micro heat pipes. Moreover, during use or assembling process, if the micro heat pipe is compressed and deformed, the heat dissipation efficiency of the micro heat pipe may dramatically be reduced.
Artificial graphite sheets (hereinafter graphite sheets) have relatively superior thermal conductivity efficiency, may smoothly be attached on any of planar surface or curved surface, and may be done any type of cutting as required. Therefore, graphite sheets are widely used as heat dissipation element of the thin mobile devices. However, graphite sheets have a very strong directionality in thermal conductivity properties. The thermal conductivity coefficient of the graphite sheet in the direction of extending surface is about 1500 W/mK, while the thermal conductivity coefficient of the graphite sheet in the thickness direction is about 15 W/mK, the difference therebetween is significant.
Since the thermal conductivity coefficient of the graphite sheet in the thickness direction is very small, the heat of the central processing unit is often unable to be immediately and efficiently dissipated through the graphite sheet which is attached thereon. Therefore, the graphite sheets cannot bring into full play the thermal conductivity efficiency thereof due to their very strong directionality in thermal conductivity properties.